A method of making ball grid array packages is described in U.S. patent application Ser. No. 09/317,957, filed May 25, 1999. According to that method, individual semiconductor devices are attached to a patterned strip, and then the devices are electrically connected to ball grid arrays on the opposite side of the strip, and then the strip is segmented to produce finished packages. A disadvantage associated with the method described in the '957 application is that each semiconductor device must be individually positioned with respect to the strip. The devices are spaced apart from each other along the length of the strip. Consequently, a separate alignment step is required for each package. In addition, since the semiconductor devices are separated from each other before they are connected to the ball grid arrays, the devices must be tested and burned-in separately. The entire disclosure of U.S. patent application Ser. No. 09/317,957 is expressly incorporated herein by reference.
Another method of making ball grid array packages is described in U.S. Pat. No. 5,858,815 (Heo). According to the Heo method, a wafer is attached to a film such that bond pads are exposed through openings in the film, and then the bond pads are connected to solder balls on the opposite side of the film, and then the layered assembly is sawed into chip-sized packages. There are numerous disadvantages associated with the Heo method. Among them is that the packages do not have sufficient stiffness. In addition, the prior art does not provide a satisfactory method of testing the Heo packages, and the prior art does not provide a suitable method of aligning the wafer with respect to the film.
The term “ball grid array” is used herein in a broad sense to include fine pitch ball grid arrays (FBGAs) within its definition.